Tread for pneumatic vehicle tyres

Abstract: A tread for pneumatic vehicle tyres comprising a central row of tread blocks (3) extending in the circumferential direction of the tyre and rows of tread blocks (1,2) arranged in the shoulder regions of the tyre is described. The rows of blocks (1,2) arranged in the shoulder regions of the tyre are separated from the central row of tread blocks (3) by circumferential grooves (4,5). The edges of the tread blocks (6,7,12,14) which laterally border the circumferential grooves extend inclined relative to the central circumferential plane of the tyre. Wave-shaped sipes or knife-cuts (21,22,23) are provided in the tread blocks (6,7,10) with the tread blocks (6,7) of the rows of blocks (1,2) arranged in the shoulder regions of the tyre being more pronouncedly divided or split by sipes (21) than the tread blocks (10) of the central row blocks (3).

Description: The present invention relates to a tread for pneumatic vehicle tyres comprising a central row of tread blocks extending in the circumferential direction of the tyre and row of tread blocks arranged in the shoulder regions of the tyre which are separated from the central row of tread blocks by circumferential grooves. Tread patterns of this kind are typically used in summer tyres. The lateral edges of the circumferential grooves are arranged parallel to the central circumferential plane. Since such tyre treads or patterns have been developed especially for summer use, the winter performance of a tyre equipped with such a profile is, in most cases, inadequate. A directional tread pattern of this kind having inclined circumferential grooves and corresponding to the preamble of claim 1 is known from DE-A-4300695. Tread patterns wherein only a portion of the circumferential groove is inclined to the circumferential plane are also known, for example from EP-A-477542 and DE-U-8809991. The object of the invention is to provide a tread for pneumatic vehicle tyres of the initially named kind which has improved winter performance so that a tyre constructed in accordance with the invention can be used as an all-year tyre. According to the invention a tread for a pneumatic vehicle tyre comprises a central row of tread blocks extending in the circumferential direction of the tyre and rows of tread blocks arranged in the shoulder regions of the tyre which are separated from the central row of tread blocks by circumferential grooves, wherein the edges of the tread blocks which laterally border the circumferential grooves extend inclined relative to the central circumferential plane of the tyre, and wave-shaped sipes are provided in the tread blocks, characterised in that the tread blocks of the rows of blocks arranged in the shoulder regions of the tyre being more pronouncedly divided up by the sipes than the tread blocks of the central row of blocks, the lateral boundary edges of one circumferential groove extend substantially parallel to each other and also parallel to the lateral boundary edges of the other circumferential groove. A zig-zag shaped course of the circumferential grooves is achieved by the edges of the tread blocks extending inclined whereby an improvement in the digging-in of the tread into snow (grip) and a better self-cleaning (snow clearing) is achieved. Through the use of wave-shaped sipes in all the tread blocks, the traction and braking action in snow is improved in particular. Moreover there are also beneficial effects on the lateral stability or lateral traction of the tyre since the onset of slip occurs later. Due to the particularly good dividing-up of the tread blocks of the rows of blocks arranged in the shoulder regions of the tyre, the tread blocks of the central rows of blocks can be less pronouncedly divided up, whereby a reduction in the running noise is achieved. According to the invention, the lateral boundary edges of one circumferential groove extend substantially parallel to one another, and also parallel to the lateral boundary edges of the other circumferential groove. By so doing, a particularly accentuated zig-zag course of the circumferential groove is obtained, whereby a particularly good grip of the pattern in snow is achieved. In accordance with a further embodiment, the sipes in the tread blocks of the rows of blocks arranged in the shoulder regions are arranged substantially perpendicular to the circumferential direction of the tyre. By reason of the perpendicular arrangement of the sipes, the lateral stability of the tread blocks is retained which has beneficial effects for the dry weather performance and in particular on the steering properties. In accordance with a further preferred embodiment of the invention, the number of tread blocks of the row of blocks arranged in the shoulder region is equal to the number of tread blocks of the central row of blocks and amounts to, depending on the diameter of the tyre, preferably 70 or more tread blocks. By so doing, more cross-edges are created giving better traction in snow and increased braking action. In accordance with a further preferred embodiment of the invention, the tread blocks of the rows of blocks arranged in the shoulder regions are arranged so as to be displaced in the circumferential direction of the tyre relative to the tread blocks of the central row of blocks. A design of this kind leads, in particular, to a reduction of the running noise and to a better running stability on dry roads, Further advantageous embodiments of the invention are given in the subordinate claims. The invention is described in the following by means of example only and with reference to the single figure which shows a schematic partial plane view of a tread design in accordance with the invention. The tread pattern shown includes two rows of blocks 1,2 arranged in the shoulder regions of the tyre, with a central row of blocks 3 being arranged between them. The rows of blocks 1,2 arranged in the shoulder regions and the central row of blocks 3 extend in the circumferential direction of the tyre. The rows of blocks 1,2 arranged in the shoulder regions are separated from the central row of blocks 3 by circumferential grooves 4,5, and comprise tread blocks 6,7 separated from one another by arch-shaped transverse grooves 8,9. The transverse grooves 8,9 taper towards the middle of the tread area, with the transverse grooves 8 being formed convex in the circumferential direction and the transverse grooves 9 concave. The central row of blocks 3 comprise tread blocks 10 each separated from one another by slightly S-shaped transverse grooves 11 and each formed from three tread block elements 12,13,14. The tread block elements 12 are separated from their respective tread block element 13 by a longitudinal groove 15 extending in the circumferential direction of the tyre. The tread block elements 13 are separated from the associated tread block 14 by an arch-shaped inclined groove 16. Two respective adjacently positioned tread blocks 10',10'' form a central tread block pair, wherein, for each pair, the longitudinal groove 15 of one of the tread blocks 10',10'' is arranged so that it lines up with the inclined groove 16 of the other tread block 10'',10' respectively. Further, the inclined groove 16 of one of the tread blocks 10',10'' extends from the longitudinal groove 15 of the other tread block 10'',10' towards the outside of the tread. The tread blocks 10 have edges 17 at their lateral ends which extend parallel to one another but inclined relative to the central circumferential plane of the tyre. Edges 18 of the tread blocks 6,7 extend parallel to the edges 17 of the tread blocks 10 and, together with the edges 17, laterally border the circumferential grooves 4,5. As a result of the inclined edges 17,18, corners 19,20 jut out into the circumferential grooves 4,5, which result in better grip of the tread in snow and thus better winter performance. Sipes 21,22,23 (which are also sometimes referred to in the art as knife-cuts) are provided both in the central tread blocks 10 and in the lateral tread blocks 6,7, wherein the sipes 21 provided in the lateral tread blocks 6,7 extend perpendicular to the running direction of the tyre. The sipes 22 provided in the central tread block elements 13 also extend perpendicular to the running direction of the tyre, whereas the sipes 23 provided in both the outer tread block elements 12,14 of a central tread block 10 extend substantially along the longitudinal direction of the relevant central tread block 10. The distance between the sipes 21 provided in the lateral tread blocks 6,7 is smaller than the distance between the sipes 21,22 provided in the central tread blocks 10, so that a more pronounced dividing-up of the lateral tread blocks 6,7 is achieved by the sipes 21. The lateral edges 17 of the central tread blocks 10 are arranged displaced in the circumferential direction relative to the lateral edges 18 of the lateral tread blocks 6,7 which results in a quieter running of the tyre.

Claims: A tread for a pneumatic vehicle tyre comprising a central row of tread blocks (3) extending in the circumferential direction of the tyre and rows of tread blocks (1,2) arranged in the shoulder regions of the tyre which are separated from the central row of tread blocks (3) by circumferential grooves (4,5), wherein the edges (17,18) of the tread blocks (6,7,12,14) which laterally border the circumferential grooves (4,5) extend inclined relative to the central circumferential plane of the tyre, and wave-shaped sipes (21,22,23) are provided in the tread blocks (6,7,10), characterised in that the tread blocks (6,7) of the rows of blocks (1,2) arranged in the shoulder regions of the tyre being more pronouncedly divided up by the sipes (21) than the tread blocks (10) of the central row of blocks (3), the lateral boundary edges (17,18) of one circumferential groove (4,5) extend substantially parallel to each other and also parallel to the lateral boundary edges (17,18) of the other circumferential groove (4,5). A tread in accordance with claim 1, characterised in that the sipes (21) in the tread blocks (6,7) of the rows of blocks (1,2) arranged in the shoulder regions have a smaller distance between them than the sipes (22,23) in the tread blocks (10) of the central row of blocks (3). A tread in accordance with one of the preceding claims, characterised in that the sipes (21) in the tread blocks (6,7) of the rows of blocks (1,2) arranged in the shoulder regions are arranged substantially perpendicular to the circumferential direction of the tyre. A tread in accordance with one of the preceding claims, characterised in that the tread blocks (6,7) of the rows of tread (1,2) arranged in the shoulder regions are separated from one another by substantially arch-shaped transverse grooves (8,9) which are formed so as to narrow from the outer side of the tread towards the middle of the tread. A tread in accordance with claim 6, characterised in that the arch-shaped transverse grooves (8,9) of a row of blocks (1,2) arranged in the shoulder regions are formed so as to extend in the same sense. A tread in accordance with claims 4 or 5, characterised in that the blocks (1) arranged in the one shoulder region are convex in form and in that the arch-shaped transverse grooves (9) of the row of blocks (2) arranged in the other shoulder region are concave in form. A tread in accordance with one of the preceding claims, characterised in that the tread blocks (10) of the central row of blocks (3) are arranged so as to be inclined relative to the circumferential direction of the tyre. A tread in accordance with one of the preceding claims, characterised in that the tread blocks (10) of the central row of blocks (3) are separated from one another by slightly S-shaped transverse grooves (11). A tread in accordance with one of the preceding claims, characterised in that the tread blocks (10) of the central row of blocks (3) collectively comprise three tread block elements (12,13,14) which are separated from one another by a longitudinal groove (15) extending in the circumferential direction of the tyre and an inclined groove (16) which is formed, in particular, arch-shaped. A tread in accordance with claim 9, characterised in that in each case two neighbouring and adjacent tread blocks (10',10'') of the central row of blocks (3) form a central tread block pair for which in each case the longitudinal groove (15) of the one tread block (10',10'') is so arranged that it is aligned with the oblique groove (16) of the other tread block (10'',10'), with the oblique groove (16) of the one tread block (10',10'') extending towards the outer side of the tread starting from the longitudinal groove (15) of the other tread block (10'',10'). A tread in accordance with claim 9 or 10, characterised in that the sipes (22) of the central tread block elements (13) of a tread block (10) of the central row of blocks (3) extend substantially perpendicular to the circumferential direction of the tyre and the sipes (23) of both the outer tread block elements (12,14) extend obliquely to the circumferential direction of the tyre and, in particular, along the longitudinal direction of the tread block (10) of the central row of blocks (3). A tread in accordance with one of the preceding claims, characterised in that the number of tread blocks (6,7) of a row of blocks (1,2) arranged in the shoulder region is equal to the number of tread blocks (10) of the central row of blocks (3) and preferably amounts to 70 or more tread blocks (6,7,10). A tread in accordance with claims 10 to 12, characterised in that the tread blocks (6,7,10), are formed and arranged point-symmetrically relative to the points lying in the central circumferential plane of the S-shaped transverse groove (11) of a central tread block pair. A tread in accordance with one of the preceding claims, characterised in that the tread blocks (6,7) of the rows of blocks (1,2) arranged in the shoulder regions are arranged so as to be displaced in the circumferential direction of the tyre relative to the tread blocks (10) of the central row of blocks (3). A tread in accordance with one of the preceding claims, characterised in that the tread blocks (6,7) of the rows of blocks (1,2) arranged in the shoulder regions have substantially the same circumferential width as the tread blocks (10) of the central row of blocks (3). A tread in accordance with one of the preceding claims, characterised in that the rows of blocks (1,2) arranged in the shoulder regions have substantially the same axial width as the central row of blocks (3).

Inventors: WINTER HANS-JOACHIM, WINTER, HANS-JOACHIM
Applicants: SP REIFENWERKE GMBH
Application year: 1994
Main classification: B60C11
IPC codes: B60C11